Light is an important factor for the successful reproduction of most fish. In this investigation, effect of different light intensities on pituitary-testis axis was studied for a period of 21 days, under normal photoperiodic regime in the tilapia Oreochromis mossambicus. The mean numbers of spermatogonia (Sg), primary spermatocytes (Ps), secondary spermatocytes (Ss), early spermatids (Est) and late spermatids (Lst) did not show significant difference between fish exposed to moderate light intensity (MLI) and initial controls or controls, whereas the mean numbers of Sg were significantly lower in fish exposed to low light intensity (LLI) compared to those of initial controls, controls and MLI groups. However, the mean numbers of Ps, Ss, Est and Lst were significantly lower in fish exposed to LLI and high light intensity (HLI) compared to those of other experimental groups. Furthermore, in the pituitary gland, weakly immunoreactive luteinizing hormone (LH) secreting cells were observed in the proximal pars distalis (PPD) region in fish exposed to LLI and HLI in contrast to the intense immunolabelling of these cells in initial controls, controls and MLI groups. The androgen receptors showed diminished immunoreactivity in the Sertoli cells along the seminiferous lobules of the testis in fish exposed to LLI and HLI, whereas the strongly immunoreactive androgen receptors were observed in the Sertoli cells in initial controls, controls and MLI groups. Taken together, these results indicate that long-term exposure to low or high light intensity light suppresses spermatogenetic process and that this inhibition is due to reduced secretory activity of LH cells in the pituitary gland and androgen secretion in the testis of the fish O. mossambicus.

Despite the omnipresence of artificial and natural light exposure, there exists little guidance in the United States and elsewhere on light exposure in terms of timing, intensity, spectrum, and other light characteristics known to affect human health, performance, and well-being; in parallel, there is little information regarding the quantity and characteristics of light exposure that people receive. To address this, the National Center on Sleep Disorders Research, in the Division of Lung Diseases, National Heart, Lung, and Blood Institute, held a workshop in August 2016 on circadian health and light. Workshop participants discussed scientific research advances on the effects of light on human physiology, identified remaining knowledge gaps in these research areas, and articulated opportunities to use appropriate lighting to protect and improve circadian-dependent health. Based on this workshop, participants put forth the following strategic intent, objectives, and strategies to guide discovery, measurement, education, and implementation of the appropriate use of light to achieve, promote, and maintain circadian health in modern society.

Payback estimates of energy efficiency investments often ignore public health externalities. This is problematic in cases where spillover health effects are substantial, such as when the application of new technology alters environmental exposures. When health externalities are included in return on investment calculations, energy efficiency programs may look more or less attractive than suggested by conventional “energy savings only” estimates. This analysis exploits the quasi-experiment provided by the 2009 Los Angeles (LA) LED streetlight efficiency program to investigate the returns on investments inclusive of an originally estimated health externality. Using the synthetic control method, we find that the LED streetlight program is associated with a lagged increase in breast cancer mortality of 0.479 per 100,000. Inclusive of the effects of LEDs on breast cancer and avoided carbon emissions, the LA LED program provides a −146.2% 10-year return compared to +118.2% when health outcomes and carbon emissions are ignored.

The Army increasingly relies on night operations to accomplish its objectives. These night operations frequently require using Night Vision Goggles and other light-sensitive devices which are strongly affected by ambient lighting, a large component of which is urban. An urban illumination model is proposed for use in tactical decision aids and wargames which would allow for more accurate prediction of target acquisition ranges and increased realism in simulations. This model will build on previous research that predicts broadband brightness as a function of population and distance from the city center. Since city population and aerosols affect light distributions, the model is being extended and generalized for multiple city types and natural and man-made aerosols. An overview of the model along with future improvements will be presented.